Fun with phase alignment

Joe Bfstplk

Axe-Master
Having some fun with Dyna-Cab and speaker phase alignment.

Dynamic in the middle, condensor and ribbon panned hard left and right.

Screen%20Shot%202023-03-29%20at%208.25.02%20PM.png


This phase alignment (dynamic 10mm closer than the other two) gives the Middle + Bridge cluck a nice finish on top....
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Apparently, according to the wavelength calculator, at 68 degrees Fahrenheit (20 Celsius) and sea level, the wavelength of 20mm (double the 10mm distance difference to give 1/2 wave cancellation frequency) corresponds to 17.15kHz, which is where it nulls the side mics a bit. You wouldn't think you could hear a difference at that frequency, given it's guitar speakers....

Incidentally, I was able to get the dynamic to sound close to the ribbon and/or condensor by simply poking around the grill cloth until i fleshed out the bottom and tamed the top just right. Note the positions in the first pic. They all sound fairly similar in those positions. The condensor and ribbon both have extended low frequencies, but the distance removes the proximity bump, and the dynamic being right on the grill cloth lets the proximity bump help its weak lows....
 
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The only thing that makes any sense to me about the 10mm offset making an audible difference is the low end of the V that the phase cancellation null puts into the frequency response curve must just be tweaking the toppest tops the speaker can put out. It's a 2x10 Super, probably loaded with Jensen P10R or P10Q speakers, which have a relatively small voice coil compared to, say, a Celestion or an EVM12L.

NVM - looked up the frequency response graph on the P10Q, and it's got a peak up between 12k and 20k that is likely the whole reason such a short distance makes an audible difference. (source: http://www.loudspeakerdatabase.com/Jensen/P10Q)

Jensen_P10Q_(Frequency_response_+_Impedance).png
 
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